Adjustable retraction delivery valve



Sept 1, 1964 Filed June 30, 1961 A. DREISIN ADJUSTABLE RETRACTION DELIVERY VALVE 2 Sheets-Sheet 1 p 19 A.DREISIN j ADJUSTABLE RETRACTION DELIVERY VALVE Filed June so, 1961 z Sheets-Sheet 2 IHIHIHH EMMA mxmom 1939mm United States Patent 3 146 791 ADJUSTABLE uurulicrion DELIVERY VALVE Aiexander Dreisin, Ulympia Fields, llL, assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis. Filed June 30, 1961, Ser. No. 121,045 6 Claims. (Cl. 137-5125) This invention relates to an adjustable retraction delivery valve for fuel injection systems.

Several means have heretofore been used to vary the amount of retraction of delivery valves for fuel injection pumps. An acceptable way of changing the retraction volume is to change the height of the retracting piston or plunger. This has heretofore been done by substituting different size pistons. In both distributor and multiple plunger type pumps, it is desirable to be able to adjust the amount of retraction volume of the delivery valve without disassembly or replacement of parts. Continuous type adjustment of the retraction of a delivery valve is beneficial in distributor type pumps due to the inherent unequal delivery of fluid by the distributor portion. For instance, in the type of single plunger pump utilizing a portion of the plunger to distribute pressurized fuel to the outlets, the economically feasible manufacturing tolerances are such that equal delivery may not be uniformly obtained. Also, the hydraulic pressure waves in the injection system will vary for the various supply lines connected to the pump to such an extent that delivery is thereby influenced in quantity. In a multiple plunger pump the delivery is not uniform due to tolerances in manufacture, and heretofore it has been proposed to vary the eifective pumping stroke of each plunger to achieve uniform delivery to the engine cylinders. These adjusting means result in substantially increased pump manufacturing cost.

To give satisfactory performance, the delivery valve for a fuel injection system should prevent irregular loss of fuel from the delivery side of the system to the supply side between strokes, should be effective to stop injection abruptly, should maintain a residual pressure in the high pressure lines after injection, and should diminish the effects of hydraulic pressure Waves existing in the high pressure lines between injections.

It is an object of this invention to provide an improved delivery valve of the retraction type wherein the amount of retraction volume may be adjusted While operating.

t is a further object of this invention to provide an adjustable retraction delivery valve wherein the retraction volume is adjustable, and the delivery opening is adjustable.

It is a further object of this invention to provide a retraction delivery valve of the type hereinbefore described which is economical to maufacture, has a minimum of working parts and gives long trouble free service.

These and other objects of this invention will be apparent to those familiar with the art from the following description when read in conjunction with the drawings in which:

FIG. 1 shows a fuel pump partially in section;

FIG. 2 is a section through the head of the fuel pump shown in FIG. 1 in which two embodiments of the present invention are illustrated;

FIG. 3 shows a third embodiment of this invention;

FIG. 4 is a section taken along the line IV-IV of FIG. 2;

PEG. 5 is a section taken along the lines V--V of FIG. 2;

FIG. 6 is a section taken along the line VIVl in FIG. 2; and

FIG. 7 is a section taken along the line VII-VII in FIG. 3.

Referring to FIG. 1, a single plunger fuel pump 11 has an upper housing portion 12 secured to a lower housing portion 113 by suitable means, not shown, and the Patented Sept. 1, 1964 lower housing is secured to an engine through bracket 14. The bracket 14- and housing 13 have bearings 16, 17 which support an engine power take-off shaft 18 which carries a pump cam 19 and a miter gear 21 which meshes with miter gear 22 nonrotatably secured to the pump plunger 23. The outer cylindrical surface of the pump plunger 23 is in fluid tight sealing relation with a bore 24 formed in the upper housing 12. The pump plunger is reciprocated in a conventional manner by the pump cam 19, fluid is admitted to an axial passage 27 in the pump plunger 23 from the pump supply chamber 26 through radial holes 23 which are cyclically blocked and opened during roation of the plunger by an adjustable control collar 29.

Referring to FIG. 2, a pressure chamber 41 is formed in the pump and includes the space between the upper end of the plunger 23 and a plug 42. The pressure chamber also includes the axial passage 27. As the plunger 23 rotates, a radial slot 43 cyclically registers with four delivery valve inlet passages 44, two of which are shown.

My novel retraction delivery valves will now be described. Two emobidments of my adjustable retraction delivery valve are shown in FIG. 2. Delivery valve 46 is interposed between one of the inlet passages 44 and an outlet passage 47 which is connected through suitable piping to a nozzle at the engine cylinder. Interior walls 43 define a bore in which a piston 51 is reciprocably mounted. The nose of the piston urges a ball 52 into sealing engagement with a conical sealing surface 53 formed in the housing. The piston 51 is biased to a closed position, in which the ball 52 is seated, by a coil spring 54 interposed between the piston and adjustable member 56. Adjustable member 56 is in threaded engagement with a threaded bore 57 of the housing. A pocket 58 is formed in the screw 56 to receive a coil spring 54 and an abutment surface 59 is formed on an axial end of the screw to limit the axial movement of the piston 51 in the axial direction away from the inlet 44.

Refering to FIGS. 2 and 6, an axially extending transverse slot 61 is formed in the end of the piston 51 which confronts spring 54 and a pair of fingers 62, 63, extend into the slot 61 so that the piston may be rotated upon the turning of member 56. When the pump plunger slot 43 register with the inlet passage 44 associated with valve 46, the plunger 23 will be moving upwardly, thereby placing the fluid in the pressure chamber under sufficient pressure to move the ball 52 and plunger 51 axially to the right against the biasing of force spring 54. As soon as the ball 52 has been moved off its seat by the fluid pressure, the larger cross sectional area of the piston 51 is subjected to the influence of the pressurized fluid and the piston quickly moves to its open position in which it contacts abutment surface 59 of screw 56.

When the piston 51 is moved by the pressure fluid to the right to its abutting relation with abutment 59 formed on screw 56, the spill edge 64 which is formed oblique to the axis 66 of the piston 51 will have moved to the right sufficiently to define an opening together with a spill edge 67 formed at the junction of the outlet passage 47 and the bore formed by walls 4-8. The spill edge 67 defines a cut out portion or recess extending axially into the wall 4% defining the bore in which the piston 51 reciprocates. As will be noted from the drawings the spill edge 67 interrupts the circumferential continuity of the bore by its extending axially relative to the bore. The circumferential dimension of spill edge 67 is a minor portion of the circumference of the bore and as illustrated extends circumferentially approximately the diameter of the drilled outlet passage 47. The spill edge 64 is formed by milling a flat 6) at an oblique angle, thereby forming a shoulder terminating at its junction with cylindrical surface 68 in edge 64.

Referring to the adjustable retraction delivery valve 71 at the left side of FIG. 2, the piston 72 is rotated by the screw '73 through a pin '74 press fit into a hole 76 and having a bayonet portion 77, as also illustrated in FIG. 4, extending into a slot 78 in the piston 72. Upon turning of the screw 73 the bayonet '77 will turn the piston to align the selected portion of the oblique spill edge fill with the spill edge 32 formed at the junction of the outlet passage 33 and the bore 84- in which the piston reciprocally moves. In this embodiment, the end 86 of the bayonet forms the abutment of the screw '73 for limiting axial movement of the piston 72 away from its ball seating position in which it is illustrated. The abutment end 86 of screw 73 abuts against a bottom surface 87 formed at the bottom of slot '78. Thus it is seen that upon rotation of the screw 73 through an angle of less than 180, it is possible to vary the retraction volume of the piston. The retraction volume of the piston is measured by the cross sectional area of the piston times the distance that the piston moves after the spill edges no longer define an outlet opening. This distance is indicated as 11. Also by screwing the screw 73 in or out one or more full turns, the abutment 86 can be repositioned to vary the maximum fuel delivery position of the piston '72 thus adjusting the opening defined by the spill edges 81, 82. It will be appreciated that when the maximum fuel delivery opening defined by the spill edges is selected it is possible to vary retraction volume of the plunger without altering the maximum fuel delivery opening, due to the threads of screw 73 and oblique spill edge 81 having the same lead angle and due to the parallelism existing therebetween.

Referring to FIG. 4, it will be seen that upon counterclockwise rotation of the adjusting screw '73, the bayonet end 7'7 of the adjusting screw will turn the piston 72 counterclockwise and place a different portion of the spill edge 81 in registry with the spill edge 82 formed on the housing 12. In FIG. the piston is viewed from the opposite direction to that of FIG. 4, and the walls 523 and 39 formed by milling a fiat on the piston 72 are clearly illustrated. The flat out on the piston permits fuel flow from one of the delivery valve inlet passages M- to the spill edge 82.

Referring to FIG. 3, a third embodiment of this invention is illustrated, and in this embodiment, the biasing spring 91 forms the torque transmitting connection between the piston 92 and screw 93. The ends of the spring 91 are fit in axially extending bores 94, 96 formed in the screw 93 and piston 92, respectively. Since these bores 94, 96 are spaced radially from the axis 97 of the piston and screw, rotation of the screw 93 will rotate the piston 92. By rotating the piston 93 one or more full turns the abutment 98 on the screw is changed in its position relative to the housing 12 and changes the delivery opening defined between the housing spill edge Mill and the piston spill edge Hi2. As illustrated, the piston has been rotated to a position wherein the portion of spill edge W2 which registers with spill edge 181 provides an early closing of the delivery opening to outlet passage 163 and therefore the largest retraction Volume is obtained during the seating of the piston against ball Iitld. It should be understood that the nut 106 must be loosened prior to screwing the screw 93 by a screwdriver engaging its end slot. Also it should be understood that a seal 137 is provided for sealing the screw relative to the housing. The locking nut 11% upon its being tightened against the housing 12, will prevent turning of the screw 93 and maintain the abutment 98 and piston 92 in the desired adjusted position.

Referring to FIG. 7, the piston 92 is shown in a fuel delivery position wherein it is in abuttin engagement with abutment 93. The spill edge 191 on the housing and the oblique spill edge 102 on the piston define the fuel delivery opening.

in fuel injection pumps it is desirable to relieve the pressure in the fuel injection line connected to the fuel delivery passages upon closing of the delivery valve to prevent nozzle drip and reduce pressure waves. This is accomplished by the retraction movement of the piston after cutting off fuel delivery. After closing of the delivery opening, further movement of the piston to its ball seating position, as illustrated in FIGS. 2 and 3, will increase the volume available to the fuel in the fuel line to the associated nozzle. This reduces the pressure in the fuel delivery line and consequently eliminates nozzle drip. By changing the portion of the spill edge of the piston which registers with the spill edge of the housing, it is possible to change the amount of retraction volume and consequently change the delivery characteristics sufficiently to compensate for dilferences in delivery to the various nozzles caused by variations in tolerances existing in the pump and nozzles, and thereby obtain uniform fuel delivery to the various nozzles of the fuel injection system. By providing an adjustable retraction delivery valve, it is possible to selectively reduce the pressure waves in the fuel delivery circuit upon closing of the valve.

An adjustable abutment is provided for the valve piston to permit selection of a desirable sized opening at the various adjusted positions of registry between the spill edges. For instance, if piston 92 of FIG. 3 is adjusted to provide a desired retraction volume, a selection of opening sizes could be obtained by rotating screw 93 one or more revolutions to provide a new position of abutment for the piston in its fluid delivery position. These stepped positions of adjustment are spaced axially from one another by the lead of threads 108, 109 formed on screw 93 and housing 12, respectively. In the new position of adjustment of screw 93 it is still possible to adjust the spill edge 162 by turning the screw 93 to place the desired portion of spill edge 102 in registry with the spill edge 101. As shown in FIG. 7, the lead angle of spill edge 1&3 is angle 17. This angle is preferably the lead angle of the threads 1G8, 109, and when so constructed, rotation of screw 93 through an angle somewhat less than varies retraction volume while the delivery opening remains constant.

From the foregoing it is evident that I have provided an adjustable retraction delivery valve which permits gradual variation of the retraction volume and step variation in fuel delivery opening. Such adjustments may be made as the pump is operating, thereby permitting adjustment of the delivery valves after assembly to balance the output of each nozzle to correct the fuel delivery inequalities inherent in the particular pump. 0 viously, for a given amount of fuel displaced by the pump plunger 23 between the closing of the inlet ports 28 and the opening of the same ports to spill fluid from the pressure chambers 41, 27, variation in the valve retraction gives control over the total quantity of fuel injected into the fuel line and out of the associated nozzle. Step variation of the fuel delivery opening defined by the spill edges permits the same pump to be used to supply fuel to engines of differing fuel volume requirements. Use of a two piece delivery valve, that is, a ball and a piston, eliminates a requirement of close concentricity tolerance between the bore for the piston and the conically tapered surface against which the ball seats.

Although illustrated for a single plunger type distributor pump, the retraction delivery valve is also useful with a multiple plunger pump, to eliminate all the parts required to provide adjustment of plunger deliveries. Instead of providing an adjustment for each plungers effective stroke, the delivery valve of this invention permits equalization of the delivery from the various plungers.

-Although only three embodiments of this invention have been illustrated, it is not intended to limit this invention except as necessitated by the scope of the appended claims.

What is claimed is:

1. An adjustable retraction fuel delivery valve assembly comprising: a housing, walls in said housing defining a bore; inlet and outlet passages in said housing in fluid communication with axially spaced portions of said bore, respectively, a two piece valve including a ball in said bore in fluid blocking relation to said inlet passage and a piston reciprocally mounted in said bore for axial movement between open and closed positions and presenting a circumferential cylindrical sealing surface in complementary fluid sealing engagement with the walls of said bore between said passages when said piston is in said closed position thereby preventing flow of fluid from said inlet passage to said outlet passage, said piston being biased toward said closed position wherein the latter maintains said ball in a closed position in which fuel in said inlet passage is prevented from entering said bore; a spill edge formed in said housing at the junction of said bore and said outlet passage, said spill edge on said housing defining an axially extending recess in said bore; a circumferential spill edge formed on the said piston at an axial terminus of said sealing surface and oblique to the axis of said piston; and means for rotatively adjusting said piston to change the portion of said spill edge thereon which registers with the spill edge on said housing when said piston is moved axially under fluid pressure to said open position.

2. An adjustable retraction fuel delivery valve comprising: a housing, walls in said housing defining a bore, an inlet passage in said housing at one end of said bore, threads formed on said housing coaxially to said bore at the other end thereof, an outlet passage in said housing in fluid communication with said bore intermediate said inlet passage and said threads, a piston reciprocally mounted in said bore for axial movement between fuel delivery and closed positions and presenting a circumferential sealing surface in complementary sealing engagement with the walls of said bore between said passages when said piston is in said closed position, a spill edge formed in said housing at the junction of said bore and said outlet passage, a circumferential spill edge formed on the said piston at an axial terminus of said sealing surface and oblique to the axis of said piston, means for biasing said piston toward said closed position wherein said sealing surface is in sealing engagement with said bore walls to prevent flow of fuel from said inlet passage to said outlet passage, an adjustment member presenting an abutment in axially confronting relation to said piston and having threads in threaded engagement with said threads formed on said housing whereby rotation of said adjustment member in full revolutions provides stepped adjustment of the fuel delivery opening defined by said spill edges when said piston abuts said abutment in its fuel delivery position, means nonrotatably connecting said adjustment member to said piston whereby rotation of said adjustment member effects rotation of said piston to change the portion of said spill edge on said piston which registers with the spill edge on said housing, the lead angle of said threads being the same as the lead angle of said spill edge formed on said piston.

3. An adjustable retraction fuel delivery valve comprising: a housing, walls in said housing defining a bore having a threaded portion at the outer end thereof, a piston coaxially mounted in said bore for reciprocal axial movement between fuel delivery and closed positions, a circumferential cylindrical sealing surface on said piston in complementary sealing engagement with the Walls of said bore when said piston is in said closed position, an inlet passage in said housing in fluid communication with the inner end of said bore, an outlet passage in fluid communication with the outer end of said bore, a spill edge formed on said housing at the junction of said bore and outlet passage, an oblique spill edge presented by an axial terminus of said sealing surface, said oblique spill edge having a predetermined lead angle, an adjustment member presenting an abutment in axially confronting relation to said piston and having threads in threaded engagement with said threaded portion for selective axial and rotative positioning to provide stepped adjustment of the fuel delivery opening defined by said spill edges upon full revolutions of said adjustment member relative to said housing, and a coil spring having one end connected to said piston and its other end connected to said adjustment member, said spring biasing said piston toward its closed position and forming a torque transmitting connection between said member and piston whereby rotation of said adjustment member changes the portion of said spill edge on said piston which registers with the spill edge on said housing to thereby selectively vary the retraction volume of said piston.

4. The structure set forth in claim 3 wherein said lead angle of said spill edge is equal to the lead angle of said threads and said oblique spill edge is parallel to said threads.

5. The structure set forth in claim 4 and further com prising a ball between said piston and said inlet passage, and a valve seat for said ball at the junction of said inlet passage and bore.

6. An adjustable retraction fuel delivery valve comprising: a housing, walls in said housing defining a bore, an inlet passage in said housing at one end of said bore, threads formed on said housing coaxially to said bore at the other end thereof, an outlet passage in said housing in fluid communication with said bore intermediate said inlet passage and said threads, a piston reciprocally mounted in said bore for axial movement between fuel delivery and closed positions and presenting a circumferential sealing surface in complementary sealing engagement with the Walls of said bore between said passages when said piston is in said closed position, a spill edge formed in said housing at the junction of said bore and said outlet passage, a circumferential spill edge formed on the said piston at an axial terminus of said sealing surface and oblique to the axis of said piston, means for biasing said piston toward said closed position wherein said sealing surface is in sealing engagement with said bore walls to prevent flow of fuel from said inlet passage to said outlet passage, an adjustment member presenting an abutment in axially confronting relation to said piston and having threads in threaded engagement with said threads formed on said housing whereby rotation of said adjustment member in full revolutions provides stepped adjustment of the fuel delivery opening defined by said spill edges when said piston abuts said abutment in its fuel delivery position, means nonrotatably connecting said adjustment member to said piston whereby rotation of said adjustment member effects rotation of said piston'to change the portion of said spill edge on said piston which registers with the spill edge on said housing.

References Cited in the file of this patent UNITED STATES PATENTS 

1. AN ADJUSTABLE RETRACTION FUEL DELIVERY VALVE ASSEMBLY COMPRISING A HOUSING, WALLS IN SAID HOUSING DEFINING A BORE; INLET AND OUTLET PASSAGES IN SAID HOUSING IN FLUID COMMUNICATION WITH AXIALLY SPACED PORTIONS OF SAID BORE, RESPECTIVELY, A TWO PIECE VALVE INCLUDING A BALL IN SAID BORE IN FLUID BLOCKING RELATION TO SAID INLET PASSAGE AND A PISTON RECIPROCALLY MOUNTED IN SAID BORE FOR AXIAL MOVEMENT BETWEEN OPEN AND CLOSED POSITIONS AND PRESENTING A CIRCUMFERENTIAL CYLINDRICAL SEALING SURFACE IN COMPLEMENTARY FLUID SEALING ENGAGEMENT WITH THE WALLS OF SAID CLOSED POSITION THEREBY PREVENTING FLOW OF FLUID FROM SAID INLET PASSAGE TO SAID OUTLET PASSAGE, SAID PISTON BEING BIASED TOWARD SAID CLOSED POSITION WHREIN THE LATTER MAINTAINS SAID BALL IN A CLOSED POSITION IN WHICH FUEL IN SAID INLET PASSAGE IS PREVENTED FROM ENTERING SAID BORE; A SPILL EDGE FORMED IN SAID HOUSING AT THE JUNCTION OF SAID BORE AND SAID OUTLET PASSAGE, SAID SPILL EDGE ON SAID HOUSING DEFINING AN AXIALLY EXTENDING RECESS IN SAID BORE; A CIRCUMFERENTIAL SPILL EDGE FORMED ON THE SAID PISTON AT AN AXIAL TERMINUS OF SAID SEALING SURFACE AND OBLIQUE TO THE AXIS OF SAID PISTON; AND MEANS FOR ROTATIVELY ADJUSTING SAID PISTON TO CHANGE THE PORTION OF SAID SPILL EDGE THEREON WHICH REGISTERS WITH THE SPILL OF SAID SPILL EDGE THEREON WHICH REGISTERS WITH THE SPILL EDGE ON SAID HOUSING WHEN SAID PISTON IS MOVED AXIALLY UNDER FLUID PRESSURE TO SAID OPEN POSITION. 